Research suggests that nearly everyone who is overweight should lose weight, but no diet has been proven effective in the long run for a majority of people

One hundred seventy-five centimeters and 83kg, Kathryn Griffith, a retired teacher in Oakland, California, counted calories for decades, trying everything from the grapefruit diet to a regimen based on cabbage soup. She also did Weight Watchers — 27 times. “I knew it wouldn’t be successful, but I went back anyway,” she said.

So earlier this year, just when Oprah Winfrey, America’s uber-dieter, renewed her resolve to snack on flaxseed, Griffith went the other way, joining a tenacious movement that is scorning the diet industry and what one pair of bloggers labels, “the obesity epidemic booga booga booga.”

This movement — a loose alliance of therapists, scientists and others — holds that all people, “even” fat people, can eat whatever they want and, in the process, improve their physical and mental health and stabilize their weight. The aim is to behave as if you have reached your “goal weight” and to act on ambitions postponed while trying to become thin, everything from buying new clothes to changing careers. Regular exercise should be for fun, not for slimming.

“Fat acceptance” ideas date back more than 30 years, but have lately edged into the mainstream, thanks in part to public hand-wringing by celebrities like Winfrey, Kirstie Alley and the tennis player Monica Seles, who said she had to “throw out the word ‘diet’” to deal with her weight gain. (Winfrey now cites her goal as being not “thin,” but “healthy and strong and fit.”)

Even television is bellying up to the bar, with Lifetime’s introduction of a hefty heroine in Drop Dead Diva and a show having its premiere this month on Fox that stresses the “reality” in reality TV. The show, More to Love, matches plus-size dates with a bachelor boasting “a big waist and an even bigger heart.” And elbowing the weight-loss guides on “health” bookshelves, is a spate of new, more diet-neutral books that track the sociology of obesity, including The End of Overeating: Taking Control of the Insatiable American Appetite (Rodale Books) by David Kessler, the former surgeon general, and The Evolution of Obesity (The Johns Hopkins University Press) by Michael L. Power and Jay Schulkin.

Adding credence to the “fat acceptance” philosophy, are recent medical studies that suggest a little extra fat may not be such a bad thing. Among the latest is a 12-year Canadian analysis in last month’s Obesity journal (www.nature.com/oby/journal/vaop/ncurrent/abs/oby2009191a.html) that confirmed earlier findings that overweight “appears to be protective against mortality,” while being too thin, like extreme obesity, correlates with higher death risk. Other recent studies have linked weight cycling (or “yo-yo dieting”) to weight gain, and to medical conditions often attributed to obesity.

Many appetite warriors have coalesced under the banner of “Health at Every Size” (or HAES), which is also the title of a book by Linda Bacon, a nutrition professor at City College of San Francisco. Bacon ran a federally financed, randomized trial to compare outcomes for 78 obese women who either dieted or were schooled in Every Size precepts. The results, published in the Journal of the American Dietetic Association in 2005, showed that HAES participants fared better on measures of health, physical activity and self-esteem. Neither cohort lost weight.